Water supplied by municipal water systems and surface and groundwater sources often contains dissolved minerals. When the dissolved minerals include calcium and magnesium carbonates and sulfates the water is said to be hard. Water hardness is measured in grains of hardness. Hardness resulting from calcium and magnesium ions produces insolvent compounds with soap which yields a grimy scum which is non-cleaning. The scum produced by the minerals in hard water leaves clothes gray and dingy and can make washing difficult, even leading to irritated and chapped skin. Of even greater concern than the precipitates formed with soap are the precipitates of carbonates when hard water is heated. The so called temporary hardness which is removed by heating hard water leaves a precipitate on the interior of hot water tanks. The precipitate acts as an insulator and thus reduces the efficiency of heat exchange between electric elements or hot combustion gases. A layer of scale only five hundredths of an inch thick can reduce heater efficiency by ten percent which--depending on hot water usage levels--may mount to over one-hundred dollars a year in lost heat.
Most of the United States, except for part of the Northwest and areas along the East Coast, have moderate to very hard water containing 3.5 to over 30 grains of hardness per gallon. Sodium ions including sodium carbonates and sulfates do not precipitate or form insoluble precipitate with soap. Water softeners employing ion exchange columns contain resin beads. The resin beads have a surface which attracts sodium, calcium and magnesium ions. The resin beads prefer calcium and magnesium ion and so if the bead surfaces are initially coated with sodium ions they will exchange sodium ions for calcium and magnesium ions, thus softening the water which flows through the ions exchange column. The column may be cleaned of calcium and magnesium ions and the surface of the beads resupplied with sodium ions by exposing the beads to a very high concentration of sodium ions. The conventional source of sodium ions is common salt i.e. sodium chloride. A brine tank containing salt crystals or pellets is partially flooded with water. The water dissolves the salt pellets and becomes sainted with salt. The saturated brine solution is then periodically run through the ion exchange column to regenerate the resin beads.
Ion exchange water softeners are regenerated typically after the passage of a fixed number of days or after the use of a fixed number of gallons of water. The process normally assumes that the brine solution used to regenerate the ion exchange column is uniformly saturated. If for any reason the brine consistency varies then regeneration may not take place often enough to prevent hard water from entering the water supply of a home or business, or on the other hand, the water softener may be set to regenerate more often than necessary. One typical approach to achieving uniform brine formation is to support the salt pellets above the bottom of the brine tank on a perforated plate. However many brine tanks are supplied without bottom supports because many suppliers of water softeners believe such supports are detrimental.
Water is introduced into the brine tank from a single source. Without a bottom support the salt in the brine tank is dissolved near the water inlet first so that the salt crystals or pellets slope down towards the water source. As the salt in the brine tank is used up the water may not be completely covered by salt.
What is needed is a way of causing the salt in a water softener brine tank to remain level as the salt is depleted.